Improved Processing Window of Contact Hole with Directed Self-Assembly of Block Copolymer Blends

Directed self-assembly (DSA) of cylindrical block copolymers (BCPs) with graphoepitaxy provides a promising strategy for contact hole shrinkage for the sub-7 nm technology nodes. It is challenging to fabricate defect-free architecture for device patterning. The aim of this work is to gain insight into the effect of blending of BCPs with different molecular weight on the self-assembly in the confined spaces. To this end, experiment and simulation were systematically performed to explore the self-assembly of various block copolymer blends. The results demonstrate that the pattern quality is significantly improved and a larger defect-free processing window is obtained in terms of template critical dimensions (CD) by adding a low molecular weight BCP. A larger defect-free processing window is obtained in terms of Template CD, from 60 nm to 87 nm by adjusting the blending ratio appropriately and the processing window expands from 18 nm to 27 nm. This work highlights the importance of optimizing block copolymer formulation.